As is well known, internal combustion engines operate by introducing fuel into fuel cylinders. Energy is released in the form of expanding gas due to rapid combustion of the fuel, which acts upon pistons and converts the chemical energy of the fuel into mechanical energy. The pistons are connected to a crankshaft, and the linear, up-and-down motion of the pistons translates into the rotary motion needed to turn the wheels of a vehicle. In order to produce the rapid combustion, fuel is mixed with intake air, either before or after the air is compressed, and then ignited in order to cause combustion. After this combustion takes place, the leftover exhaust gases are forced out of the cylinder and subsequently expelled into the environment or, more recently, treated and/or recirculated into the engine intake, which is known as Exhaust Gas Recirculation (EGR).
During the turbo charging of diesel, for example, although not limited thereto, the pressure of the exhaust gases in most cases is less than the intake air, and exhaust gases can therefore not be efficiently recirculated without measures being taken for achieving a sufficient supply of exhaust gases. Such measures may take the form of, for example, venturi solutions, exhaust throttles or inlet throttles.
By placing a venturi in the inlet flow, an advantageous difference in pressure between the exhaust channel side and the air intake inlet channel side is achieved locally in the venturi, and exhaust gases, which are removed upstream of the turbo, can be fed into the inlet pipe of the engine. A reduced NOx level is obtained as a result of the lower combustion temperature. However, traditional venturi solutions have been associated with disadvantages in the form of, for example, reduced engine power through high pressure losses, together with increased fuel consumption and smoke development.
U.S. Pat. No. 7,036,529 (Berggren et al.), which is hereby incorporated by reference in its entirety, obviates problems associated with the prior art by providing an EGR system which includes a streamlined body arranged to be displaced in the longitudinal direction of a line near the EGR inlet. The body allows for achievement of a variable venturi effect and in this way a variable suction effect and mixture of the mixed flow. The system also includes an actuator for displacing the body forwards and backwards in the line.
Intake air and EGR then flows to the engine. Fuel is traditionally injected directly into the cylinders of a diesel engine, resulting in an inhomogeneous charge and a diffusing flame where the injected amount of fuel is metered to control power output. However, injecting the fuel directly in the cylinders does not allow for optimum fuel/air mixture for combustion.
Therefore, it would be beneficial to have a superior system and method for exhaust gas recirculation (EGR) venturi diesel injection.